The proposed studies involve an examination of the posttranscriptional modifications of messenger RNA (mRNA) molecules in normal and cataractous lens tissue. Biochemical and molecular biological techniques will be used to (1) identify and characterize the structure of specific mRNA molecules, their precursors and degradation products and to (2) detect, isolate and characterize purified enzymes associated with specific structural modifications in the RNA studied. Correlations will be made between changes in the modification enzyme system, RNA structure and mRNA functionality in differentiating cells at various stages of lens development, growth and aging in normal cataractous lens tissue.